Sometimes you just want to go back in time. While in life, that's not usually possible, Windows is a different story: System Restore lets you take your PC back to an earlier point in time, letting you restore your PC to an earlier state, in which programs and settings revert to the way they were in the past. Of course, the main reason for doing this is that you installed something that deteriorated the smooth functioning of the PC, and your aim is to restore the PC to a condition in which it runs well.

If your goal is more drastic: You want to clean out or restore the computer to mint condition, Windows 8 has built in tools for this. I explain these in How to Refresh or Reset Your Windows 8 PC. Just one update to that article is that in Windows 8.1, to get to these options, you go to Settings, and then choose in Settings | Update & recovery, and choose Recovery. From there, you use the Refresh and Reset tools as described in the earlier article.